Health Related Questions About Indoor Radon
March 29, 2011
What is the evidence that indoor radon exposure is really a health risk?
The earliest evidence of radon-related health risk came from long-term cohort studies of underground miners conducted over the past 60 years. This evidence was of sufficient strength by 1988 that the World Health Organization’s International Agency for Research on Cancer (IARC) classified radon and its short-lived decay products as known human carcinogens (Group 1 or Class A). The National Cancer Institute has led the on-going study of 68,000 international underground miner radon risks. The National Academy of Sciences’ extensive assessment of the miner and other health risks associated with indoor radon is found in Health Risks of Exposure to Radon (BEIR VI) which is available at www.nap.edu/openbook.php?record_id=5499 Based upon this report, the U.S. Environmental Protection Agency (EPA) completed EPA Assessment of Risk of Radon in Homes which is available at www.epa.gov/radiation/docs/assessment/402-r-03-003.pdf Since the 1980s, more than 40 residential case-control studies have been conducted. Overall, these studies reflected increased risk of lung cancer in homes with elevated indoor radon. In the mid-portion of the past decade, data from a number of residential case-control studies were pooled which allowed for more rigorous risk assessment (7 studies in North America; 13 studies in Europe; 2 studies in China). The risk estimates from the three sets of pooling studies virtually matched the risk estimates from the miner cohort studies – – – thus, giving very strong evidence that radon exposure in the home increases the risk of dying from lung cancer.
Further information about radon health risks is found in the World Health Organization’s WHO Handbook on Indoor Radon – A Public Health Perspective (a free copy is available at whqlibdoc.who.int/publications/2009/9789241547673_eng.pdf The strength of the evidence of the health risk associated with indoor radon exposure led WHO to recommend that (economically developed) countries establish radon reference levels, where mitigation would be recommended, at 100 Becquerels per cubic meter (Bq/m3) or 4 picoCuries per liter (pCi/L). The WHO recommendation is 33% or one-third lower than the EPA 4 pCi/L Threshold for Action. The Health Physics Society, an organization of 5,500 radiation safety professionals from 44 countries, recommends reducing exposures below 2.7 pCi/L www.eurekalert.org/pub_releases/2009-11/hps-hps112509.php and hps.org/documents/radon_position_statement.pdf
I have heard that there is research that suggests that exposure to low levels of radon exposure do not pose a health risk; is that true?
Yes, there have been “ecological” studies that suggest that there is not a risk of lung cancer at low levels of radon exposure. However, ecological studies should not be used for risk assessment. Some of those who argue hormesis (low doses of ionizing radiation are safe) are supported by those in the nuclear and chemical industry The National Academy of Sciences reviewed the health risk associated with exposure to low levels of ionizing radiation, including radon, and found, “The scientific research base shows that there is no threshold of exposure below which low levels of ionizing radiation can be demonstrated to be harmless or beneficial,” said committee chair Richard R. Monson, associate dean for professional education and professor of epidemiology, Harvard School of Public Health, Boston. “The health risks – particularly the development of solid cancers in organs – rise proportionally with exposure.”
Further information is available at books.nap.edu/catalog.php?record_id=11340 Other organizations that share the perspective of the National Academy of Sciences include: National Council on Radiation Protection Health Related Questions About Indoor Radon March 29, 2011 Board of Regents University of Minnesota Page 2 of 2 (UNSCEAR).